A boiler for heating or hot water is a device for applying heat to heating water or direct water (hereinafter, referred to as a ‘heating medium’) by a heat source to heat a desired zone or supply hot water, and is configured to include a burner for burning a mixture of gas and air, and a heat exchanger for transferring combustion heat of combustion gas to the heating medium.
A boiler produced in the early days employed a heat exchanger of heating a heating medium using only sensible heat generated upon combustion of a burner, whereas a boiler produced recently is a condensing boiler designed to improve thermal efficiency, which is provided with a sensible heat exchanger for absorbing sensible heat of combustion gas generated in a combustion chamber and a latent heat exchanger for absorbing latent heat generated upon condensation of water vapor that is contained in the combustion gas undergone heat exchange in the sensible heat exchanger. Such a condensing boiler is commercialized in an oil boiler as well as a gas boiler to thereby contribute much to an increase of boiler efficiency and fuel expenses reduction.
As described above, a conventional heat exchanger of a condensing type configured with a sensible heat exchanger and a latent heat exchanger has a structure in which an air blower, a fuel supply nozzle, and a burner are typically installed at an upper part of a housing, and the sensible heat exchanger and the latent heat exchanger, in which heat exchange fins are coupled to an outside of a heat exchange pipe, are sequentially installed inside the housing below the burner.
However, such a heat exchanger of a condensing type has a problem in that a dimension of the heat exchanger should be increased due to the structure in which the air blower is located at the upper part of the housing and the sensible heat exchanger and the latent heat exchanger are longitudinally located inside the housing.
As the prior art for addressing such a problem, minimizing the dimension and improving heat exchange efficiency, a heat exchanger is disclosed in Korean Patent Registered Nos. 10-1321708, 10-0581578, and 10-0813807, wherein the heat exchanger is configured with a burner located at a center thereof and a heat exchange pipe wound on a circumference of the burner in a coil shape.
FIG. 1 shows a cross-sectional view of a heat exchanger of a condensing boiler disclosed in Korean Patent Registered No. 10-0813807. A heat exchanger 40 shown in FIG. 1 is configured to include a burner 10 installed to discharge downward combustion gas, a heat exchange pipe 20 wound on a circumference of the burner 10 in a coil shape so as to heat water suppled inside the heat exchanger 40 to a desired temperature by heat generated at the burner 10 to thereby provide the heated water as heating water or hot water, and a partition wall 30 installed at a lower side of the heat exchange pipe 20 in a horizontal direction to form a passage of combustion gas. As shown in FIG. 1, the heat exchange pipe 20 is arranged to have an inclined surface 21 that is inclined from an outside of a body to an inside thereof by a predetermined angle to be directed to a central direction of the burner 10, and one end of a connecting pipe 33 is connected to and installed at a body of the partition wall 30, which forms a communication hole 32 thereinside, thereby connecting one side of the heat exchange pipe 20 to the other side thereof through the other end of the connecting pipe 33.
However, the heat exchanger disclosed in the prior art documents has a disadvantage in which a torsional phenomenon occurs while the heat exchange pipe is helically processed to cause a difficulty in processing an entire surface of the heat exchange pipe in a uniform shape.
Also, when a heat exchange pipe is undergone a bending process, damage may occur upon the bending process due to a difference of a strain rate between an inside surface of the heat exchange pipe toward a center of a burner and an outside surface thereof opposite the inside surface, and thus the heat exchange pipe exchanging heat with combustion gas may have a limitation to be formed in a wider width. As a result, there is a structural limitation in which a sufficient area for processing an irregular shape promoting a turbulent flow on a surface of a heat exchange pipe is not secured as a configuration for more improving heat transfer efficiency between a heating medium and combustion gas.
In addition, the conventional heat exchanger has problems in that an installation structure of the heat exchanger is complicated because a housing H is separately provided as a configuration for tightly sealing an outer circumference of the heat exchange pipe 20 being helically wound, and a heat source of combustion gas is not fully transferred to a heating medium flowing inside the heat exchange pipe 20 because heat transferred to the housing H is directly radiated and dissipated to an outside thereof, wherein the heat is transferred to the housing H while the combustion gas generated by combustion of the burner 10 passes a longitudinally separated space of the heat exchange pipe 20 to flow through a space between the heat exchange pipe 20 and an inner wall of the housing H.
Additionally, the conventional heat exchanger has problems in that heat generated by the combustion of the burner 10 is transferred to a plate 11 for fixing the burner 10 to thereby cause an overheating, and also an insulating material or a heat dissipation fin at an outside of the plate 11 should be additionally provided in order to prevent such an overheating such that a complicated structure and a heat loss are induced.